The market has been dominated for a long time by a back-and-forth battle between WJZ and WBAL. Since the mid-1990s, most years ended in some version of a split decision, with both stations claiming victory. It was all mind-numbingly predictable.

Then, last week, came a set of Nielsen numbers for January showing WJZ (Channel 13) scoring a clean sweep over WBAL (Channel 11) — winning every competitive news time period. That defines dominance.

It's never wise to get too excited about one month's worth of ratings. But those January results come after WBAL had lost almost half its audience this fall at 4 p.m. in the aftermath of the end of "Oprah." The recent Nielsen numbers pose the question: What's going on at Baltimore's NBC affiliate as it begins a crucial February "sweeps" ratings period?

The station known for Jayne Miller, Rod Daniels and its "live, local and late breaking" motto looks as if it might be losing its ratings edge — if not more.

In July, the station did not renew longtime first-string co-anchor Marianne Banister, choosing to let Daniels go solo at 11 p.m.

On Sunday, after the Super Bowl and the start of the second season of NBC's"The Voice," WBAL will add its early anchor, Donna Hamilton, to the late-news lineup, again teaming Daniels with a female co-anchor as it tries to "put its best foot forward," in the words of general manager Dan Joerres.

Year to year, the station's flagship newscast has lost 45 percent of its viewers ages 25 to 54, the demographic on which most TV news ad sales are made. (WBAL's average audience of late-news viewers in that age group dropped from 53,709 to 29,637 during the last year, according to Nielsen. That includes live viewing as well as those viewers who record the news and then watch it within 24 hours.)

Despite such numbers in afternoon, early evening and late night, Joerres says WBAL is not in decline. In fact, he says, 2012 is going to be a "monumental year" for his station.

"WBAL has been a dominant news station for the last few decades, and I think the station is still, at its core, the same TV station that it was last year at this time," Joerres said in an interview Thursday after the January figures were published.

The executive, who came to WBAL last year from Milwaukee, attributed the station's ratings in January largely to a weak NBC prime-time lineup and what he characterized as a continuing inability by Nielsen to accurately measure Baltimore viewing with the Local People Meters it introduced in July 2009.

"I do think any station can be No. 1 with the volatility of where the meters are placed," he said, referring to the 606 homes selected by Nielsen to represent 1.097 million households in the Baltimore market.

Nationally, there has been a pattern of the highest-rated stations showing the largest losses when Nielsen shifts a market from viewer diaries to meters. But WJZ is measured by the same meters.

As for NBC's prime-time schedule, it has been a disaster of a lead-in for the 11 p.m. news at stations across the country. Nothing better typifies what an NBC affiliate manager like Joerres was up against than NBC's Monday newsmagazine, "Rock Center with Brian Williams," which features special correspondents such as Chelsea Clinton.

Last Monday, "Rock Center" drew a nationwide audience at 10 p.m. of 3.293 million viewers. Reruns of "Castle"(ABC) and "Hawaii Five-O"(CBS) in the same time slot drew 6.71 million and 7.45 million viewers, respectively. And "Rock Center" was the show that replaced"Playboy Club" in NBC's wreck of a fall lineup.

Starting this week, in an attempt to mollify affiliates, NBC moves "Rock Center" to 9 p.m. Wednesday, where it will not be a direct lead-in to the late news. Meanwhile, the network's 10 p.m. Monday time slot will be taken over by"Smash,"one of TV's most anticipated midseason debuts.

WBAL should also get a solid ratings boost Sunday from NBC's presentation of the Super Bowl — and, perhaps, even a better one this summer from the Olympics.

"If you look at the Super Bowl or 'The Voice' and 'Smash' and the Olympics, everything that we have coming up says this is going to be a monumental year for WBAL," Joerres says. "And at our core, I know that our number of viewers is the same and that our station continues to be dominant from a news standpoint."

Not surprisingly, WJZ general manager Jay Newman disagrees with Joerres about which station is the dominant TV news source in Baltimore. But despite the Nielsen numbers to back him up at the moment, the CBS executive isn't gloating.

"The January results are great, and we're very happy with them," Newman says. "But we also know this is a very competitive media landscape with very, very difficult competition. And we need to continue to work hard and focus on continuing to deliver a great news product."

Hamilton's debut after the Super Bowl at the late-news anchor desk alongside Daniels will be watched closely.

Banister's departure after 15 years was a prime example of a high-performing veteran being dumped to save money in a tough economy. But in cutting costs, WBAL may have lost something else.

Banister brought a bit of big-market gloss — if not class — to a newscast often filled with crime scenes and gritty rowhouse visuals.

"I had a former general manager in Los Angeles who told me something I have always remembered," Banister said last week when she was asked to comment on the WBAL ratings. "He said as hard as it is to become No. 1 in television, it is even harder to stay there. You cannot become complacent. You cannot take viewers for granted. And you must always strive for quality."

Banister — who still lives in Baltimore, where she runs a media consulting firm — added that she believes an "experienced" newsroom and anchor desk are the kinds of factors that make for a winning newscast.

"Even in tough economic times, experience is well worth the cost, because, at least in television, if you cut back too far, you risk hurting your news product," she said. "And then you risk losing the loyalty of your viewers. Basically, you give them a moment to try another station on for size. And they may decide they like it better."